Effect of Ota Industrial Estate effluents on surface water quality of Oruku River, Ota, South Western Nigeria

Abstract

The effect of industrial effluents on surface water quality of Oruku River was investigated in this study by analyzing selected water quality indicators such as pH, dissolved oxygen (DO) and total dissolved solids (TDS) were examined amongst other physicochemical parameters using standard methods. Results show that, average pH of the surface waters ranged from 5.53±0.31 to 6.23±0.45 with SR3 having the highest value. This indicates that all the water sources were alkaline. The effluents had an average pH range of 5.95 ± 1.12 to 6.40 ± 0.48. A comparison of these average pH values with effluent quality standards indicated that the effluents pH were below limit (6.5-9.5). The average BOD levels in surface water ranged from 1.94 ± 0.95 for SR-4 to 3.78 ± 1.61 for SR-1. DO average values in surface water was found to be higher at SR-1 with a mean value of 5.36 ± 1.55 and lower at SR-2 with a mean value of 3.05 ± 0.68. The mean COD value for surface water ranged from 108.66 ± 73.03mg/L to 232.81 ± 155.46mg/L. SR-3 had the highest COD average value of 232.81 ± 155.46mg/L while there was a reduction at SR-5 to an average value of 108.66 ± 73.03mg/L. The high COD value in the surface water indicates that gross-organic pollution of the water source may be from other sources such as agricultural and urban run-offs.